Comparative Performance Evaluation of Convolutionally Coded and LDPC Coded OFDM System over AWGN and SUI-5 Fading Channel

Orthogonal Frequency Division Multiplexing (OFDM) is a very attractive technique for high data rate transmission with good bandwidth efficiency. OFDM system utilize the cyclic prefix (CP) to mitigate the effect of inter symbol interference (ISI) produced by the multipath effect of wireless channel. The CP insertion only mitigates the effect of inter block interference of OFDM symbols, whereas the intra block interference remain present in the OFDM symbol. The intra block OFDM symbol interference degrades the error performance of the OFDM system. In order to improve the error performance of the OFDM system forward error correction scheme can be utilized. Many FEC schemes for single carrier and multicarrier systems have been proposed in the literature. Convolution and LDPC codes are two popular coding schemes for FEC. In this paper we have considered Convolution and LDPC codes for improving the error performance of OFDM system. The BER performance of convolution ally coded & LDPC coded OFDM is evaluated for various code rates in AWGN and fading channel. We have also compared the performance of coded OFDM system with an OFDM system without FEC.